A hydraulic tool in one form comprises a hydraulic torque wrench. A hydraulic torque wrench includes a ratchet mechanism with a drive including a double-acting hydraulic cylinder. The cylinder is reciprocated to operate the ratchet to provide torquing as high as thousands of foot pounds. The reciprocation of the hydraulic cylinder is typically accomplished using a hydraulic pump with flow being selectively directed to opposite sides of the cylinder.
Existing pumps for operating hydraulic torque tools can generally be categorized as manually operated, programmable automated, and automated without the use of programming.
With an entirely manually operated pump, the operator must cycle the pump through the different portions of its cycle manually. With a programmable automated system, the operator must first program the pump by entering such information as torque wrench model or size, torque to be achieved, desired pressure and dwell time at the end of operation. These pumps are not user friendly, as they can be difficult to program. The automated pumps without the programming function typically use sensors within the pump or valve to indicate when the tool has reached the end of its stroke, and then shift a valve to begin the next step of the cycle. These pumps can be unreliable because of the variable signals that can be sensed before the tool reaches the end of its stroke. The variable signals can be due to hose decompression, tool backlash, the size of the tool and the length of the hoses used in the system.
The present invention is directed to solving one or more of the problems discussed above in a novel and simple manner.